It is known, for example from WO2013180619A1, in an agricultural implement, to feed granular or powdered material from a material container via a meter to a channel that takes up the material in an air stream and that feeds the material onward to, for example, a plurality of furrow openers.
The meter comprises a meter housing, in which a metering rotor is rotatably disposed.
The air stream is typically achieved by a fan or a pump, which produces an overpressure in the channel that leads the air stream.
It is desirable to ensure that the overpressure is maintained in the entire channel in order to reduce energy consumption, and it is a challenge to introduce the material in the channel without losing the overpressure.
One way of achieving this is to provide the material container with a seal-tight lid, so that the overpressure is maintained all the way up in the material container.
Another way of achieving this is to utilize an injector, in which a vacuum suction to the channel is achieved according to the Venturi principle.
Another method is to provide a meter that acts as an air lock and thus prevents the overpressure in the channel from leaking up into the material container, allowing normal pressure in the material container.
Normal pressure in the material container is advantageous, since it is difficult to provide a large material container with a similarly large lid which is sufficiently seal-tight.
One problem is that the environment in which the agricultural implement is used and the material being fed often give rise to large amounts of dust and dirt, which makes it difficult to achieve good seal-tightness.
An additional problem is that the material to be fed can disturb the function of the metering rotor, so that the rotor blades are prevented from being sealed against the inside of the meter housing.
Based on the fact that it is desirable to provide a meter that acts as an air lock, there is a need for an improved meter, in particular a meter which reduces air leakage in a reverse direction from the meter outlet to the meter inlet.